1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus of performing cell re-search between heterogeneous networks.
2. Related Art
Wireless communication systems are widely spread all over the world to provide various types of communication services such as voice or data. In general, the wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available radio resources. Examples of the multiple access system include a time division multiple access (TDMA) system, a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, etc.
CDMA2000 supports a voice service and a data service through a CDMA channel. Standards included in the CDMA2000 are IS-2000, IS-95, and IS-895. EV-DO is a part of the CDMA2000 and is a 3-rd generation CDMA standard. The EV-DO provides a packet data service with a high data rate. The EV-DO originally stands for “EVolution, Data-Only”, and is recently also referred to as “EVolution, Data-Optimized”. The EV-DO is based on high rate packet data (HRPD) defined by the 3-rd generation partnership project 2 (3GPP2) standardization organization. The HRPD is a high-speed CDMA-based radio data technology developed by Qualcomm Inc.
With the widespread use of wireless communication systems developed into various systems, there are many cases where heterogeneous networks coexist in the same region. The heterogeneous networks are networks that implement different radio access technologies (RATs). For example, a wideband-CDMA (WCDMA) system and an HRPD system may coexist in one region.
A mobile terminal needs to perform a handover between the heterogeneous networks for various reasons such as a required quality of service (QoS), a load of a base station, and so on. Accordingly, there is a need for a method of performing cell re-search to effectively support a handover between heterogeneous networks.